Seal



Patented Oct. 1, ,91940 UNITED STATES PATENT OFFICE SEAL i Gunnar A. Wahlmark, Rockford, Ill.

7 Claims.

The invention relates generally to fluidl seals, and more particularly it relates to a mechanical seal construction which prevents leakage of iluids, either ,liquid or gaseous,` along a rotary drive a shaft.

The primary object of the invention is to provide, in connection with the projecting rotary shaft of a pump or the like. a new .and improved mechanical seal of simple construction.

Another object is to provide a mechanical seal with a non-elastic diaphragm of great exibility so that it is self-aligning and will not crystalline due 'to a slight runout on the vseal face, together with novel means for clamping the stationary edge of the diaphragm.

This application is a division of my copending application Serial No. 66,009, iiled February 27, 1936, now Patent No. 2,159,720, issued May 23, 1939.

liti

parent from the following description, taken in connection with the accompanying drawing, in

which: Fig. l is.a sectional view 'taken along the axis of a rotary pump embodying the features of the invention. Fig. 2 is an enlarged portion of Fig. 1 showing the elements of the mechanical seal in central longitudinal section along the axis oi the shaft. For purposes of disclosure, the preferred form ci the invention is illustrated in the drawing and will hereinafter be described in detail as applied to a particular form of pump. but it is to be understood that this disclosure is not intended as a limitation of the invention to pumps, nor to the particular type of pump illustrated, it being contemplated4 that various changes might be made by those skilled in the art to adapt the invention te other types of rotary apparatus and to .other types of pumps Without departing from the spirit and scope of the invention as delined bythe appended claims.

As shown in the drawing, the invention is embodied in a pump of the rotary type having M an elongated casing comprising a horizontally disposed cup-shaped member l0, forming one end of the casing, within which, is disposed a pump chamber il and pressure actuated means designated generally as Hf for controlling .the discharge from the pump. Secured over the open end of the cup-shaped member I is atrend closure i2 completing the casing and having a tubular extension i2 whichforms a bearing hub. A gasket i3 interposed betweenfthe cup-shaped as member I0 and the end closure l2 to makethe Other objects and advantages will become ap-v joint fluid-tight so that the casing, in addition to housing-the pumping and control means, constitutes an auxiliary reservoirv i4. Depending from the cup-shaped member I0 and removably secured thereto in fluid-tight relation is a strainer cup I5 within which is supported a double screen strainer i6.

The pump chamber I l has one end wall formed by the end closure I2, while the other end wall is formed by a plate'l spaced from the end clol0 sure'by an annular ring I9 constituting the periphery of the pump chamber. Housed within the pump chamber and operable to draw fluid into the chamber and forcibly discharge it therefrom are rotary pump elements of the general l5 character disclosed and claimed in my copending applications Serial No. 675,218, filed June l0, 1933, now Patent No. 2,132,813, dated October 11, 1938, and Serial No. 14,017, led April 1, 1935, noW Patent No. 2,146,037, dated February 7, 1939, comprising an internally toothed rotor 20 rotatable within the annular ring I9. Positioned eccentrically within the rotor 20 and meshing therewith over a portion of the circumference only is a roller 2| and interposed in the space 25 left by the 'eccentric mounting of the rotor and roller is a crescent-shaped element 22 completing the pump chamber. The axial dimensions of the rotor and roller are such that the end faces have a sliding but huid-tight engagement vwith the endl Walls of the chamber. Here the roller 2| is the driving element and to that end is secured as by a key 25 to a shaft 26 journaled in the axial extension l2 and projecting outwardly thereof.

The preferred form of the invention is herein associated with the projecting end of the shaft 26 to prevent fluid from leaking out along the shaft. Referring particularly to Fig. 2 of the drawing, the seal comprises a bushing 2l fixed to and rotatable with the shaft 26 and engaged 40 in an endwise direction by a non-rotatable seal ring 29supported by a flexible diaphragm 29', The outer edge ofthis diaphragm is secured in leak-proof relation to an elongated housing or casing member 3I and, 'as illustrated, is posi- 45 tioned in a recess 30 in the end of the housing 3l and is clamped against a shoulder v3| by means of a nut 32 and an apertured bellfshaped member or cap 29" which is positioned intermediate the4 diaphragm 29 and the nut 32 with 60 its outer peripheral edge bearing against the diaphragm to clamp it against the shoulder 3l'. and its inner edge bearing against the nut 32.-* The cap 29 is preferably formed 4of a resilient or springy metallic material and with a somewhat convex shape adjacent the shaft so that the nut 32 engages the cap around its inner edge. An expansive coil spring 32 acts between the nut 32 and the ring 29 to press the ring axially and maintain contant contact between an annular lapped face on the ring and the adjacent annular end surface on the bushing 21. This spring is preferably in the form of an expanding helix with the turns spaced so that it may be compressed flat to afford a maximum deection in a minimum space.

To 'prevent leakage of fluids, either liquid or gaseous, between the bushing 21 and the shaft 26, the bushing is preferably formed from relatively soft metal with a tapered outer surface 21 along which the internally tapered ring 28 of stronger metal may be driven axially to distort the bushing inwardly into leak-proof relation to the shaft.

In accordance'with the present invention, Ythe diaphragm 29' is constructed from an extremely flexible non-elastic material such as a cloth or textile fabric which is more or less limp as compared with diaphragms of metallic'or semi-rigid materials, so that the material in itself does not materially resist movement or oscillation of the seal ring. Being of a non-metallic character, such a diaphragm is free from internal stresses which tend to cause failure when the diaphragm is distorted at various angles. ployed for the diaphragm is preferably a textile fabric devoid of any rubber and is neither elastic nor resilient. 'Ihe fabric is, in fact, known as airplane cloth, impregnated and otherwise treated so as to be fluid-proof, and is of such a character as to resist the harmful actions of the various liquids or gases with which the device is to be used. The diaphragm is necessarily nonelastic because friction tends to rotate the seal ring and would thus distort an elastic diaphragm to a greater or lesser extent as the friction varied. 'I'his would cause oscillation of the seal ring 29 resulting in 'a' chattering and breaking of the seal.- If desired, the fabric may be relativelylthin, and a plurality of laminations thereof employed to form the diaphragm.

. The fabric of the diaphragm is centrally apertured to conform with the inner diameter of the seal ring 29, and is secured at its inner edge to the ring 29 in leak-proof relation by means such as a clamping bushing 34. The bushing 34 as shown hereinhas a flange which is positioned between the diaphragm and the spring 32' and has a tubular portion which extends through the seal ring in spaced relation to the shaft, and is interlocked with the ring as by outward bending or riveting to hold the flange and the ring firmly clamped to the fabric of the diaphragm.

It is believed readily apparent that the invention overcomes difficulties which may arise due to inaccuracies in the manufacture of the parts of the device, and particularly the housing 3| and the nut 32. In the manufacture of threaded parts such as the nut and housing, it is diiilcult to obtain an assembled structure in which the l end surface of the nut is perfectly parallel to the shoulder 3|. The cap member 29 compensates for variations in these surfaces and serves as an equalizing means transmitting the clamping force of the nut uniformly to the periphery of the diaphragm. Furthermore, due to the resiliency of the cap, it serves as an automatic takeup means andeiliciently secures the periphery The material em- .diaphragm to maintain the diaphragm in contact with said shoulder and an annular resilient portion adjacent said shaft, and an apertured nut device threaded on said housing and having an annular surface surrounding said aperture and spaced substantially inwardly from the peripheral edge of the cap for engagingthe resilient portion of said cap to maintatinthe cap in uniform engagement with said diaphragm throughout its periphery. y

2. In combination, a housing having an opening and an annular surface at one end thereof, a rotary shaft extending through said opening, and a sealing means for the opening comprising a collar secured in fluid-tight relation on the shaft, an annular sealing member positioned to bear against said collar, an annular, flexible diaphragm of substantial width secured at its inner edge to said sealing member and at its outer periphery against said annular surface, an apertured spring metal cap having a flange on its peripheral. edge positioned against said diaphragm to maintain the diaphragm in contact with said surface and having an inner edge closely adjacent and surrounding said shaft, and a nut device threaded on said housing for engaging the portion of said cap adjacent said shaft to maintain the cap in uniform engagement with said diaphragm throughout its periphery.

3. In combination, a housing having an opening and a shoulder about the opening, a rotary shaft projecting through the opening in the housing,v a collar secured in fluid-tight relation on said shaft and a rotary seal cooperating with said collar to-prevent leakage along the shaft comprising an annular sealing member positioned to bear against said collar, an annular flexible diaphragm forsupporting said sealing member having the inner periphery secured to said sealing member and its outer periphery disposed against the shoulder on said housing, a bell-shaped cap of springy metal centrally apertured to be received over the shaft and throughout its periphery bearing against said diaphragm to clamp the same against the shoulder on said housing, a nut threaded onto the housing and having an annular edge engaging said cap along the edge of its central aperture adjacent the shaft to tension the same to exert clamping force on said diaphragm., and a compression spring interposed between said cap 'and said sealing memberl urging the latter into contact with said collar.

4. In a machine having an apertured casing and a rotary shaft projecting through said aperture, the combination of a mechanical seal between said shaft and said casing comprising an exteriorly tapering bushing formed from. relatively soft metal and encircling said shaft, a

shaft and the bushing, a seal ring encircling the shaft in spaced relation thereto and adapted for annular flat surface contact with said bushing A pregnated fluid-proof fabric, a bushing having a y in an endwise direction, an annular flexible diaphragm of impregnated fluid-proof fabricfa bushing for securing the inner edge of said diaphragm in leak-proof relation to said seal ring having a radial flange adapted to be disposed on one side of the diaphragm and a tubular portion extending through `the diaphragm and the seal ring and securing the seal ring on the opposite side of the diaphragm to clamp the same therebetween, a spring urging the seal ring into contact with the bushing secured to the shaft, and means for securing the outer circumference of the diaphragm in the casing comprising a bell-shaped cap of spring metal having a central aperture through which the shaft extends when the periphery of the cap bears against the diaphragm to clamp it against the casing, and means detachably secured to the casing and engageable with the cap along the entire edge defining said central aperture to lock the cap in place. .e

5. In a machine having an apertured casing and a rotary shaft projecting through said aperture, the combination of a mechanical seal between said shaft and said casing comprising a bushing fixed about and rotatable with the shaft and fitted to the shaft to prevent leakage of fluid therebetween, a seal ring encircling the shaft in spaced relation thereto and adapted for annular surface contact with said bushing in endwise direction, an annular exible diaphragm of imtubular portion extending through said diaphragm and into engagement with said seal ring and a radial flange disposed on the side of said diaphragm opposite said seal ring to clamp the diaphragm therebetween in leak-proof relation, means urging said seal ring into engagement with the bushing on the shaft, and means for securing the outer periphery of the diaphragm in leakproof relation against an annular shoulder formed on the casing comprising a bell-shaped cap of spring metal disposed in said recess 'centrally apertured to be received over the shaft and throughout its periphery having a flange bearing againstsaid diaphragm to clamp the same against the shoulder in said housing, a nut threaded onto the housing and having an annular portion engaging said cap along the face thereof adjacent its central aperture to tension the same to exert clamping force on saiddiaphragm,`and a compression spring interposed between said cap and said sealing member urging the latter into contact with said collar.

6. In combination, a housing having an opening forming an annular shoulder, a rotary shaft projecting through the opening in the housing, a collar secured in fluid-tight relation on said shaft and a rotary seal cooperating with said collar to prevent leakage along the shaft comprising an annular sealing member positioned to bear against said collar, an annular flexible diaphragm for supporting said sealing member having its inner, periphery secured to said sealing member and its outer periphery disposed against the shoulder on said housing, an annular resilient mlember centrally apertured Vto be received over the shaft and throughout its outer periphery bearing against said diaphragm to clamp the same between the shoulder on said housing and the said annular resilient member, and a nut threaded onto the housing and engaging said annular resilient member along its inner edge and closely adjacent the shaft to tension the same to exert clamping force on said diaphragm.

7. In a pump, in combination, a housing having an opening and an `annular shoulder at one end thereof, a rotary shaft extending through said opening and a sealing means for the opening comprising a collar secured in fluid-tight relation on said shaft, an annular sealing" member posi- -tioned to bear against said collar, an annular housing and having an annular portion closely 4adjacent said shaft engaging said cap along its inner edge and acting to maintain the cap in uniform engagement with said diaphragm throughout its periphery.

GUNNAR A. -WAI-ILMARK. 

